Expanding clamp for a tube bending machine



Dec. 2, 1958 E. F. MELLINGER EXPANDING CLAMP FOR A TUBE BENDING MACHINE 2 Sheets-Sheet 1 Filed Feb. 1. 1954 m m m m v ERNEST F. MELLINGER BY Knox & 161w! Arrolnzv m PM? FOR APPLICANT Dec. 2, 1958 E. F. MELLINGER- EXPANDING CLAMP FOR A TUBE BENDING MACHINE 2 Shets-Sheet 2 Filed Feb. 1,

IN V EN TOR. ERNEST F. MELLINGER I l l I J ATTORNEY IN MY FOR APPLICANT United States Patent p 1 2,862,540 EXPANDING CLAMP FOR A TUBEBENDING MACHINE Ernest. F. Mellinger, San Diego, Calif assignor to The Ryan Aeronautical Co., San Diego, Calif 21 corporation of California App ic tion e uary 95 ,S.e a N ,350 6 Claims. c1. 153-30 The present invention relates generally tomet-al working-equipment and more particularly Ito-an expanding clamp for a tube bending machine.

In present-types of tube bending machines one end'of the tube beingbent'is clamped between jaws'while the 'tube is formed around a;grooved block. -A considerable straight length of the tube must be held inthe jaws to ensure a firm-grip during the bending operation,-and the tube must be heldby considerable pressure. The straight portion of the-tube held between the jaws is often cut off and discarded after the bending operation, a 'process which is wasteful and costly. Moreover, this portion of the-tube is;often damaged -by the clamping pressureof the jaws, this-being particularly true when bending light gauge tubing. The'present invention enables a tube tobe held firmly at the end with a minimum of wastematerial and also prevents damage -tothe' tube by crushing in the jaws of the machine.

The primary object of this invention is to provide an expanding clamp which positively secures the end of a tube being bentby locally expanding and clamping the tube between interfitting beadedand grooved elements -in-the bending machine.

Another object of this invention is to provide an expanding clamp which is adjustable :s o;that=the straight ortion of-tube clamped in'the inachine may ;b e varied -to anyreguired len'gthL '2 v Another object of this invention is to provide an expandingclamp -which "may be fittedfto many existing types-of-tube bending machines and whichniay -be constructed -in any "required size to accommodate standard -tube sizes. i

'lfinally'; it is an jobject to provide an expanding clarnp --'ofthe aforementioned character whichj is' simple safe and convenient for workmen to operate, and 'whichwill givegenerally efiicient-and durable servicei V 7 With these-and other objects definitely in view, this invention consists in the novel construction, combination .and arrangement of elements and portions, as will be hereinafter fully described in'the specification, particularlypointed outirrthe claims, and illustrated fin the drawings which form a material part of this disclosure f and wherein similar characters of reference indicate' sim- 1 ila'ror identical -"elements-and; portions throughout' the specification and =t-hroughout'thewiews of thedrawings "-and in which: 7 '1 I V 1 Pig. lflis'a persp ive. vi w of e'exp nd -sl m assembly attached to a tube bending machine.

Fig. 2 is an end-elevation view of thedevice.

Fig. 3 is a-topplanview.

Fig. 4 is an enlarged ;1 ine*4 4 of'Figg2 i an nlar f a menta y iewa tp ti 2 S ow m dea theexn adi ndr clamping the end of a tube. i p v 1 Fig 6 is er ra ta n a y se i n new-taxman the fline16f6of'Eig; 5.. I l

sectional taken on" the Referring now to the drawings, the structure of'the device includes a clamp jaw 10 and a forming jaw 12, which are secured to the frame 14 of a conventional tube bending machine, shown fragmentarily in Figs. 2 5 and 3aforreference purposes. The clamp jaw 10 has a semi-circular groove 16 and the forming jaw 12 has a corresponding semi circular gr oove 18, so that when the-jaws are clamped together the grooves form a cylindrical bore 20 in which the tube to be bent is inserted. 10 The forming jaw 12 has an arcuate end 22 with a form ing' groove 24incorporated therein and comprising an extension of the groove 18. i

p :ses a-fluid pressure actuating cylinder 26 ct -conventional design, having extending piston rod 28. Secured in the end of the piston rod 28 is an expanderjpin 30'which passes through an expanding -mandrel-32; The-mandrel 32 rests'on' a support tube 34 having an integral base plate 36, which is secured against the :end of the actuating cylinder 26. Secured to the actuating cylinder 26 is a bracket 38 carrying a roller guide 40,'which-is slidable on a guide rail 42 mounted on one side of the forming jaw 12. This guide rail 42 assists in aligningthe mandrel 32 .for axial V adjustment in the bore 20. o I

-. The bracket; 38 .has a.substantially L-shaped portion 44 having at the ends thereof lugs 46 and; 48. The .upper lug 46lis secured to-the base plate 36 while the .lower lug :48 is secured to an attachment plate 50 on the lowerendo'f the actuatingcylin'der 26, suitable screws 51 gandr52 being -.used "for. the attachment. The upper portion. of .-the :bracket :38 is. extended outwardly to provide. a face plate 54. .The roller l'guide 4 0 comprises a generally UAShaped channel 56,1one side-of which is extended .to constitute a..c1amp plate 58 having a pair of parallel slots- 60 therein. '.'I.he.roller guide is secured to the bracket-38 by bolts 62 and nuts'64, the slots;,60 permittingradial adjustment. of the roller guide relative to th'e actuating cylinder 26. :Within' the channel 56 are rollersz66rotatably mountedon pins 68' to pro- 40 vide a, friction free contact against the guide rail-42.

;l he'guide rai1;.5l2..is .secured to a pair. or spaced support bars 70 extending outwardly'frorn; amounting plate 12 secured to the side of r the forming .jaw 12 by means of screws -14. Atathe lower end of .theguide rail '42 is a -;stop pinil6 to limit the. downwardmovement of the actuating cylinder; and .expandingmandrel assembly.

-The mandrel tJShoWn best-in l-ligsiv 5 .and 6, comprises-four segments 7,8 sof a cylinder having a tapered central -b ore 80. The segments .78 collectively have r;an.,9utwardly projecting annularbeadl82 adjacentthe upper end thereof andian inwardly disposed annular groove 84;;sp'aced below..said .bead. 1 The segments are biased inwardly by a,spring'-.,86, fitted inthe groove 84. The expander pin-iitl comprisesu a'tapered head 88 shaped to fit thebore 80 of the mandrel 32. :Extending downwardly from the vhead 88 is a shank 90 having a ,serewthreaded end 92 ,whichuis screwed into the end -;the i smrodztt Theeupporttube is; fitted with a pair of inwardly projecting retaining screws 9Aiadjacent the upper end to prevent inadvertent removal from the expander pin 30. illhe inside of the bore- 20-has a'pluralityv of spaced ring grooges -96 shaped similarly to thecontour'ofthe bear 82. 11 86 i g grooves 196 are located sothat the upper-groove isjaligned; with;,the:bead 82 when the base plate 3 6 -is flush againstpthe lower surface of-theforming jaw 12 andislamniawno. ,iIIl order. toutilize the remaining ring grooves 96, spacing washers 98 are fitted ,Q-VeLz-the :SlllQpQllQtllbQgil -tbetvyeenathe base plate 36 andgthe jaws 10. 'and;,12, said spacing washers being equal in thi ckness to the distancebetwcenthe individual iPae oQYe v The expanding clamp comp .into the bore 20 until the end of the tube extends slightly below the head 82, the expanding mandrel assembly being inserted from below and held against the lower surface of the jaws and 12. Pressure is then applied .to the actuating cylinder 26 to retract the piston rod 28,

so pulling the tapered head 88 downwardly through the mandrel 32 and forcing the segments 78 outwardly so that the bead 82 forces the tube 100 into the ring groove 96, as shown in Figs. 4 and 5.

When interconnecting lengths of tubing which have been bent, a certain length of straight tubing is necessary at each end to facilitate attachment of the couplings or the like. The straight length may be varied in the present device by adding or removing spacing washers 98 to control the depth to which the mandrel assembly is inserted in the bore 20. In the drawings, two of these spacing washers 98 are shown as an example, the bead 82 being aligned with the second ring groove 96 below the uppermost ring groove. When no spacing washers 98 are used, the bead 82 is, of course, aligned with the uppermost ring groove 96.

With the end of the tube 100 clamped tightly by the mandrel 32,.the tube is bent around the forming groove 24 as shown in dotted line in Fig. 4. The tube is bent with the, aid, of a conventional forming mouse or the like, the construction and use of which are fully understood by those skilled in the art. When the tube is bent to the required position, .the pressure in the actuating cylinder 26 is released or reversed causing the piston rod 28 to extend. The segments 78 are pulled inwardly by the spring 86, so releasing the bead 82 from the tubing compressed into the ring groove 96. The jaws 10 and 12 are then opened to facilitate removal of the tube 100. The only waste portion of the tube 100 is the fractional end portion containing the formed bead, a

which may be removed in a suitable manner to leave the'required length of tube. I

The roller guide 40 and guide 'rail 42 assist the alignment of the mandrel 32 when the assembly is inserted in the bore 20, and also-stabilize the actuating cylinder" 26 throughout the complete range-of adjustment. The slots roller guide 40 so that a single actuating cylinder 26 may be used with several sets of jaws and mandrels.

It will be evident that the present device may be installed on many types of conventional tube bending machines or incorporated therein by machining the necessary ring grooves 96 in the existing jaws 10 and 12 and adding the guide rail 42 and its supporting structure to each forming jaw 12.

The operation of this invention will be clearly comprehended from a consideration of the foregoing description of the mechanical details thereof, taken in connection with the drawing and the above recited objects. It

will be obvious that all said by this invention. 7

Further description would appear to be unnecessary. It is understood that minorvariations from the form of the invention disclosed herein may be made without departure from the spiritand scope of the invention, and

objects are amply achieved that the, specification and drawing are to be considered as merely illustrative rather than limiting. 7 v

, j I ,claim:

60. permit considerable radial adjustment ofthe 1. In a tube bending machine, separable jaws having confronting faces defining a substantially cylindrical bore therebetween, said faces having grooves therein, said grooves being spaced apart a uniform distance axially of said bore, a segmented mandrel slidable in said bore, an outwardly extending head on said mandrel, said grooves being shaped and positioned to receive said bead, a tapered expander pin longitudinally slidable in said mandrel, traction means operatively connected to said expander pin for longitudinal movement thereof, a bracket fixed to said traction means, a guide rail mounted on one of said jaws, said bracket being slidable on said guide rail longitudinally relative to said bore, spacers between said traction means and said jaws to adjust the longitudinal position of said mandrel in said bore, said spacers having a thickness dimensionally equal to the distance between said grooves, whereby said mandrel may be held with said bead selectively aligned with said grooves.

2. In a tube bending machine, separable jaws having confronting faces defining a substantially cylindrical bore therebetween, said faces having grooves therein, said grooves being spaced apart a uniform distance axially of said bore, a segmented mandrel slidable in said bore, an outwardly extending head on said mandrel, said grooves being shaped and positioned to receive said bead, a tapered expander pin longitudinally slidable in said mandrel, a fluid actuated cylinder having an extended piston rod, said expander pin being attached to said piston rod, a rigid support tube between said cylinder and said mandrel, and spacers between said cylinder and said jaws to adjust the longitudinal position of said mandrel in said bore, said spacers having a thickness dimensionally equal to the distance between said grooves, whereby said mandrel may be held with said head aligned with individual grooves.

3. In a tube bending machine, separable jaws having confronting faces defining a substantially cylindrical bore therebetween, said faces having grooves therein, said grooves being spaced apart a uniform distance axially of said bore, a segmented mandrel slidable in said bore, an outwardly extending bead on said mandrel, said grooves being shaped and positioned to receive said bead, a tapered expander pin longitudinallyslidable in said mandrel, a fluid actuated cylinder having an extended piston rod, said expander pin being attached to said piston rod, a rigid support tubebetween said cylinder and said mandrel, a bracket fixed on said cylinder, a guide rail mounted on one of said jaws, said bracket being slidable on said guide rail longitudinally relative to said bore, and spacers between said cylinder and said jaws to adjust the longitudinal position of said mandrel in said bore, said spacers having a thickness dimensionally equal to the distancebetween said grooves, whereby said mandrel may be held with said bead aligned with individual grooves. Y

4. In a tube bending machine, separable jaws having confronting faces defining a substantially cylindrical bore therebetween, said faces having grooves therein, said grooves being spaced apart a uniform distance axially of said bore, a segmented mandrel slidable in said bore, an outwardly extending bead on said mandrel, said grooves being shaped and positioned to receive said head, a tapered expander pin longitudinally slidable in said mandrel, a fluid actuated cylinder having an extended piston'rod, said expander pin being attached to said piston rod, a rigid support tube between said cylinder and said mandrel, a bracket fixed on said cylinder, a radially adjustable roller guide :on said bracket, a guide rail mounted on one of said jaws, said roller guide being slidable on said guide'rail longitudinally relative to said bore, and spacers between said cylinder and said jaws to adjust the longitudinal position of said mandrel in said bore, said spacers having a thickness dimensionally equal .to the distance between said grooves, whereby said 'mandrel may be held with said therebetween, said faces having grooves therein, said grooves being spaced apart a uniform distance axially of said bore, a segmented mandrel slidable in said bore, an outwardly extending bead on said mandrel, said grooves being shaped and positioned to receive said head, a tapered expander pin longitudinally slidable in said mandrel, a fluid actuated cylinder having an extended piston rod, said expander pin being attached to said piston rod, a rigid support tube between said cylinder and said mandrel, a bracket fixed on said cylinder, a radially adjustable roller guide on said bracket, a guide rail mounted on one of said jaws, said roller guide being slidable on said guide rail longitudinally relative to said bore, a stop pin in said guide rail to limit the travel of said roller guide, and spacers between said cylinder and said jaws to adjust the longitudinal position of said mandrel in said bore, said spacers having a thickness dimensionally equal to the distance between said grooves, whereby said mandrel may be held with said head aligned with individual grooves.

6. In a tube bending machine, separable jaws having confronting faces defining a substantially cylindrical bore therebetween, said faces having grooves therein, said grooves being spaced apart a uniform distance axially of said bore, a segmented mandrel slidable in said bore,

an outwardly extending bead on said mandrel, said grooves being shaped and positioned to receive said bead, a tapered expander pin longitudinally slidable in said mandrel, a fluid actuated cylinder having an extended piston rod, said expander pin being attached to said piston rod, a rigid support tube between said cylinder and said mandrel, inwardly projecting screws in said support tube to retain the same on said expander pin, and spacers between said cylinder and said jaws to adjust the longitudinal position of said mandrel in said bore, said spacers having a thickness dimensionally equal to the distance between said grooves, whereby said mandrel may be held with said bead aligned with individual grooves.

References Cited in the file of this patent UNITED STATES PATENTS 

